This invention relates to the field of optical fiber image scanners and more particularly to a hand-held plastic optical fiber scanner which contains no electric circuits within the scanner head and which is compact, which provides higher contrast ratio and scanning resolution, which increases scanning speed and which reduces the power required for illumination of the image being scanned.
Optical fiber scanners, per se, are well known. For example, U.S. Pat. No. 4,467,196 discloses a hand-held pen-shaped single fiber optical scanner for reading a bar code which is scanned by transmitted single wavelength pulses which are reflected back through the same single fiber. The frequency and spacing of the transmitted light pulses, and the spacing of the code bars, are chosen such that the pulses reflected from the bar code occur between the transmitted light pulses; however, the scanner is capable of detecting only the transitions or edges of the code bars, requires a beam splitter and does not have a color scan capability, i.e., it can provide only black and white ("1"and "0") signals with no gray levels.
A pen-shaped hand-held optical scanner with a rotary displacement encoder is disclosed in an article titled, "Compact Imaging Apparatus for a Pen-Shaped Hand-Held Scanner", by Haga, Fujieda and Okumura, in Proceedings of the SPIE, International Society for Optical Engineering, Vol. 3019, pp. 168-173, February 1997.
The following U.S. patents further show the state of the prior art of optical scanners:
U.S. Pat. Nos. 3,610,891: 3,784,794; 3,786,181; 3,869,599; 3,870,396; 4,011,007; 4,748,680; 4,702,552; 4,760,421; 4,847,490; 4,978,850; 5,015,064; 5,061,036; 5,074,641; 5,121,459; 5,159,656; 5,159,576; 5,258,858; 5,367,596; and 5,673,344.
The disclosures of all of the above-cited patents and publication are expressly incorporated herein by reference.